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C. E. WILLIAMS.

PORTABLE AUDJPHONE TRANSMITTER.

APPLICATION FILED DCT.3.1917.

Patented July 29, 1919.

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Pmmm M 29, 1919,"

2 SHEETS-SHEET E. WILLIAMS.

PORTABLE AUDIPHONE TRANSMITTER.

APPLICATION FILED on. 3. i911. 39

cnmns E. wrLLmins, or cmcaeo, ILLINOIS, ASSIG-NOR T0 wrnnmms nnrrcunerondomrm, a conromrron or scorn DAKOTA.

ronmnnn aomrnon's-rmnsmzrrna Specification ofIletters Patent. I PatentedJuly 1919.

Application med October a, 1917. Serial No. 194,455.

To all whom it may concern:

Be it known that I, CHARLES E. Wrzmsns, a citizen of the United States,and resident of Chicago, in the county of Cook and State of Illinois,have invented an Improvement in Portable Audiphone-Transmitters, ofwhich the following description, in connection with theaccompanymg'drawings, is-a specification, like letters on the drawingsrepresentin like parts.

y present invention is an improved transmitter, constituting a hearingaid for deaf or partially deaf persons, and is intended primarily foruse as a portable instrument in connection with the wbll knownaudiphone.

The manufacture of portable instruments to aid hearing, presents manydifiiculties, particularly in t type of hearing aids known as theWilliams tion, efiiciency and sensitiveness of the trans- "tancevFurthermore, in such prior trans-v mitters employed. It will beappreciated that all types of hearing aids intended to be earned by theperson must be compact and suitable for transporting and yet must beextremely delicate, accurate and capable of operation with a relativelysmall amount of electrical energy. In the manufacture of suchtransmitters; particularly, dificulty has been ex erienced because ofthe size and deptho instrument heretofore necessary for eflicient use.With the. ordinary type of transmitter, if made shallow and of circularform, a nasal or thin sound was the result, which was very objectionableto the user, and was unsuitable for use at any great dismitters, ifit'was desired to employ two double transmitters, to produce a powerfulfour transmitter instrument, the extreme bulkiness resulting wasobjectionable for a portable device.

- My present invention not only enables me to produce a ver thin andcompact trans mitter, but also, y reasonof the im roved features. ofconstruction, to be explained, I

have discovered that such thin transmitter can be so made as tosuccessfully eliminate the objectionable nasal sounds above mentioned.In fact, I can make so compact a V transmitter that same may be formedwith two double transmitters hinged together, thus constitutingafour-transmitter Instrue arrangement, construe-- used by men, or in theordinary small shopping bag, when used by women, and the transmitterneed not be removed from either receptacle during use; I accomplish thisresult by utilizing a thin, relatively oblong and flat aluminum plate oneither side 'of relatively shallow, circular transmitters,

which oblong plates are covered with leather,

fabric or suitable textiletmaterial, turning under the plates the edgeof the leather or fabric, which leather or fabricfcushions thetransmitter," thus allowing for a certain resiliency, which, inpractice, prevents the lighter outside mechanical noises frominterfering with the transmission of articulation. The advantages. ofthis construction seem to entirely eliminate the objectionable, roaringor sea shell sound which was heretofore present in certain transmittersof s'ufiicient depth to secure the proper amount of reverberatory spacetherein. Furthermore, theoblong construction permits a" considerablerange or scope'in varying the transmitters by changing the tone andcharacter of the same and of the sound transmitted, by making chamberslonger or wider without increasing the depth. Thus the thin and compactarrangement of my improved transmitter is reserved and enables the sameto be carried in the pocket or shopping bag, as above explained. When itis realized that'heretofore a four-transmitter audiphone wasnecessarilyso bulky asto re; quire. a separate box and handle-to ca it,

.loeing approximately eight inches long, elght inches wide and fourinchesideep, whereas my invention permits a four-transmitter audiphoneof equal power and greater sensitiveness to be constructed of a sizecapable of fitting within the inside coat pocket, the practicalimportance vof. niypresent invention will be emphasized. l'believe thatboth the form anl construction of my transmitter shown herein isdistinctly new, and therefore I Wish toclaim' all novel features thereofbroadly.

Other features-9f the invention, details of construction .and novelcombinations of parts, will be hereinafter out and claimed,

more pointed:

Referring to the drawings, illustratin a preferred embodiment of theinvention,

Figure 1 is a front view, with the outer covering partly. broken away,of my thin oblong double transmitter;

Fig. 2 is a side view of the same,

Fig. 3 is a cross sectional view on the'line 33 of Fig. 1; and

Fig. his a diagrammatic view on a reduced scale, of the four-transmitterinstru-. ment. v-

Figs. 5 and 6 are front and side views, the

latter in crosssection, of a modified form of the invention.

I have herein illustrated, in the drawings, a double transmitter, but itwill be appreciated that I may hinge together two of these thin oblongcasings, each-containing a double transmitter, folding the same equallyiand thus producing a, powerful four-transmitter instrument, owith onlydouble thethickness. In my completed four-transmitter instrument. as nowmade, the entire thickness of the same is usually under two and a hainches, whereas the width of the apparatus would be under four inchesand the length approximately six inches.

The double transmitter, substantially as shown in the drawings, with oneabove the other, in the oblong casing, gives an extremely satlsfactory,delicate and eflicient device, and it is also feasible to make this typeof transmitter with a single instrument of half the length of theapparatus shown. I prefer to arrange the instrument, with the doubletransmitters as shown, having 7 said transmitters facing the oblongreverberatory chamber in the main casing, said transmltters beingcarriedby the front plate or cover which is spaced from the main casmg,or back of the device, to form a reverberatory chamber, with means -topermit the entrance of the sound waves into the oblong reverberatory.chamber.

I prefer to use aluminum for the plates,

- covering the same with leather, although other suitable material inplace of said aluminum plates may be employed, andany desired fabric maybe utilized. Referring to the drawings, the main casmg or back of theinstrument comprises an aluminum plate 1, which is fitted into thecorresponding groove or recess 2 in the rim 3, so as to prevent a flushappearanceon the back, which is entirely covered by the leather ortextile material 4. The rim 3 is also pro vided with a rabbet, asindicated at 5,

around .which the'covering 4 is ,glued or held. This arrangement, '5,presents a shoulder for the late 6, also'covered with leather or fabricaround its-edges, which late 6 carries the transmitters -8 and- 9. hecover 10 is also incased, in leather or fabric 11 having the ends of thesame doubled over as indicated at 12 and 13' suflicient .so as to restupon. the shoulders of the transmitters 8 and 9, as clearly shownin'Fig. 3.

The usual binding posts 14:, .15, are shown withconnections 16,, 17.

. Through the plate 6 is a plurality of holes 18, 18, formed mainly andprincipally ti) permit the plate 6 to vibrate freely, affording a freeair passage through the holes 18 in the plate 6, as indicated by thearrows .20, into the lon oblong reverberatory chamber 19. By

aving the transmittercarrying plate 6 secured to the oblong mem- I ber'1around the edge of the rabbet 5 and the thicknesses of the leathercovering 4 and 7 extraneous noises are eliminated, and the accuracy,efliciency, and delicacy of the instrument is improved. The plates areheld together by suitable screws121, 21, and the handle 22 isalso'provided.

As already explained, the construction of my improved transmitters,enables a con siderable-change intone to be secured bysimply enlargingthe area of the transmit-- ters Without changing the depth, and theconstruction of the two plates 1 and 6, with a yieldingmaterial, such asleather or fabric,

interposed between their edges, whereby the transmitters are held spacedfrom the back i 1 and each transmitter opens into the 'samereverberatory chamber 19, presents a construction which is compact,thin, and at the same time produces a clear and' powerful tone,eliminating all r,oarin and enabling a sgecially attractive, porta ledevice to be ma e. H

Also, where a powerful four-transmitter instrument 1s made in accordancewith my invention, it is still sufficiently compact to I be portable ina convenient way. By ing the device covered with leather or textilematerial, an attractive and protecting finish is given,-while the use ofthe cover ing as the yielding and tightly compacting means between vthetwo aluminum sheets, 1

soundby differently placing the partition. I 4

as desired, As shown in Fig. 6, the transmitters in'this form of theinvention, 25 and 26, are held by .a thin metallic plate 27, similar totheplate 6, in Fig. 3', which is attached around its side to the rim .28and cover 29, all being inclosed with a leather casing 3 0, Aplurality-of perforations 31 In this form I employ a closed are hereshown in preference to a series of perforations around each transmitter,as in the prior construction. This permits the vibration of thetransmitters and of the entire plate 27, admitting air through the holes31 into the reverberatory recess 33. The back plate 34 is also provided,being spaced. from the holding plate 27 by a rim 35, extending aroundthe edge portions, and forming a second reverberatory chamber 36,

a plurality of holes or opemngs 39 in the transmitters 25 and Q6 uponthe electrode into this chamber 36. I prefer to add an intermediatepartition 40, dividing the chamber 36 into two separate portions,'0nefor each transmitter and by varying the position of this partition I cansecure a considerable change in the characteristics of the sound.

In both forms a neat, compact double transmitter is provided in anextremely narrow space, and a four-transmitter instrument may be madewhich is still sufiiciently cogpact for convenient portability.

y invention is further described and defined in the form of claims asfollows:

1. In a device of the kind described, the combination of a plurality oftransmitters in a reverberatory chamber, a plate carrying saidtransmitters and having openings around its edge permitting vibration ofsaid plate, freely, by allowing access of the air to and from the underpart of the plate said plate forming. part of the reverberatory'chamber, said transmitters being in substantially the same plane.

In a device of the kind described, the combination of a plurality oftransmitters in a reverberatory chamber, a plate carrying saidtransmitters and having openings around its edge permitting vibration ofsaidplate freely, by allowing access of the air to and from the underpart of the plate, said transmitters being in substantially the sameplane and means to change the character of the sound ineach transmitterby a partition, dividing the reverberatory chamber adjacent eachtransmitter.

3. In a device of the kind described, the combination of'a plurality oftransmitters, a vibrating plate carrying said transmitters, a coverspaced from the plate and partially inclosing the transmitters, meansuniting said plate to the cover in said spaced relation with anon-metallic cushioning material therebetween, said plate having aplurality of openings therethrough into the inclosure adjacent eachtransmitter to enable said plate tovibrate freely and to allow a flow ofair into said inclosure formed and cover during such vibration. I

In" testimony whereof, I have signed my name tothis specification, inthe presence of two subscribing witnesses.

CHARLES E. WILLIAMS.

- Witnesses HARvEY JOHNSON, M. M. 'MAonnNNAN.

by the plate

